What’s your advice for aspiring writers?
Learn to take constructive criticism well; it will make you a better writer. Learn to ignore destructive criticism; it is intended to hurt, not help, and reflects poorly only on the character, motives and antisocial nature of the critic. But learn also to be mindful that harsh criticism is sometimes warranted and dismissing it will only prevent you from improving your craft.
Expect rejection letters and resist the impulse to dismiss them off hand. Some editors will take the time to make helpful comments if they see merit in your writing; it is a kindness on their part to offer advice, constructive criticism or encouragement. They have better things to do than to comment on rejected works. Appreciate these comments and take them as a compliment–someone cared enough to give you expert advice that, if heeded, might help you make a sale when you revise and resubmit the manuscript elsewhere. (But first, write a thank you note to the editor that offered advice or helpful comments.)
Stand your ground when you feel strongly about your writing. Nothing that has ever been written by anyone has garnered universal appeal. If you have something worthy of being said, you will strike a responsive chord with some readers. You will also likely strike a dissonant chord with others. You need only read the reviews of top writers in Amazon, Goodreads or elsewhere to see that this is the case for all writers if they are popular enough to garner thousands of reviews–just look at the one-star reviews that they were given by those who bought their books along side the glowing five star reviews.
You can’t please everyone–no one can. First and foremost, make sure you please yourself while maintaining a healthy, honest critical eye on your own writing–the rest will follow in time.